Hybrid EV Transmission Layout for Shift-Without-Power-Interruption
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Solution Overview
Problem
Existing series-parallel hybrid variable speed transmission systems in hybrid electric vehicles suffer from low torque transmission efficiency, limited vehicle acceleration, high motor torque and speed range requirements, complex structure, and power interruption during gear shifting, leading to increased costs and reduced fuel efficiency.
Innovation Solution
A multi-position variable speed transmission system with an engine, first and second motors, input and output shafts, intermediate shafts, and synchronizers or clutches, allowing for gear shifting without power interruption and multiple operating modes, including electric vehicle, series hybrid, and parallel hybrid modes, with reduced component count and simplified control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If series-parallel hybrid variable speed transmission system is used, then engine can work under optimum condition, but torque transmission efficiency is low and vehicle acceleration is limited
Solution Approach 1:
The patent implements a multi-position variable speed transmission system that dynamically switches between series hybrid mode, parallel hybrid mode, and direct drive mode. This dynamic configuration allows the system to adapt to different driving conditions, enabling the engine to operate at optimal points while directly coupling the motor to the drive wheels for improved torque transmission efficiency and acceleration performance.
2Device complexity
If engine and motor have only one position each, then structure is simple, but they work in low efficiency areas affecting fuel consumption
Solution Approach 1:
The patent employs a variable speed transmission system with multiple operating positions that dynamically adjusts the connection configuration between engine, motor, and drive wheels. This enables both engine and motor to operate across multiple efficiency zones, significantly improving overall fuel consumption while maintaining manageable structural complexity through intelligent control.
3Power
If motor has large torque and speed range, then vehicle performance is improved, but cost of drive motor and use cost increase
Solution Approach 1:
The patent divides the power delivery function between engine and motor across different operating modes. The motor does not need to cover the entire torque and speed range alone, as the engine supplements in parallel hybrid mode and direct drive mode. This segmentation allows using a smaller, more cost-effective motor while maintaining high vehicle acceleration performance.
4Speed
If gear shifting is implemented in existing systems, then speed variation is achieved, but power interruption occurs reducing running smoothness
Solution Approach 1:
The patent implements a gear shifting mechanism with a synchronizer that maintains continuous power transmission during gear changes. The synchronizer engages intermediate gears to bridge the transition between different gear ratios, ensuring that power flow from engine through motor to drive wheels remains uninterrupted, thus maintaining running smoothness while enabling speed variation.
Data Source
AI summary
A multi-position variable speed transmission system for a hybrid electric vehicle includes an engine, a first motor, a second motor, an input shaft, an output shaft, a first intermediate shaft, a second intermediate shaft, and first, second and third synchronizers. The input shaft is connected to the engine. The intermediate shafts are respectively connected to the first and second motors. The input shaft is connected to the first synchronizer. The output shaft is connected to the second and third synchronizers. The first intermediate shaft is connected with a first transmission gear. The second intermediate shaft is connected with second transmission gears. The first or second transmission gear respectively meshes with one of gears on the output shaft.